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Qin Huang

Publications and source records attributed to Qin Huang.

At least 19 recordsLinked to original sources
PubMed2007

The histopathologic spectrum of carcinomas involving the gastroesophageal junction in the Chinese.

Carcinomas involving the gastroesophageal junction are common in China. The histopathologic characteristics of these cancers have not been systematically investigated. Reported are 41 such resected cancers from Chinese patients (30 men, 11 women). Their mean age was 62 years. The mean tumor size was 4.4 cm (range, 2 to 9 cm), and 58% were poorly differentiated. An unusual spectrum of tumor differentiation was observed, including adenocarcinomas (83%), adenosquamous (32%), colloid (2%), signet-ring (10%), squamous (5%), oncocytic (7%), pancreatic acinar (12%), and neuroendocrine (5%) carcinomas. Cancers with multiple types of differentiation in the same tumor were identified in 37 cases (90%). The adjacent gastric cardiac mucosa showed hyperplasia, oncocytic, and pancreatic acinar metaplasia, and mild chronic inflammation. Dysplasia was uncommon (n = 6). Barrett esophagus was not identified. Carcinomas involving the gastroesophageal junction in the Chinese are morphologically distinct, heterogeneous, and may be of esophageal origin.

Adult↗
PubMed2006

Improving cell therapy--experiments using transplanted telomerase-immortalized cells in immunodeficient mice.

Cell therapy is the use of stem cells and other types of cells in various therapies for age-related diseases. Two issues that must be addressed before cell therapy could be used routinely in medicine are improved efficacy of the transplanted cells and demonstrated long-term safety. Desirable genetic modifications that could be made to cells to be used for cell therapy include immortalization with human telomerase reverse transcriptase (hTERT). We have used a model for cell therapy in which transplantation of adrenocortical cells restores glucocorticoid and mineralocorticoid hormone levels in adrenalectomized immunodeficient mice. In this model, clones of cells that had been immortalized with hTERT were shown to be able to replace the function of the animals' adrenal glands by forming vascularized tissue structures when cells were transplanted beneath the capsule of the kidney. hTERT-modified cells showed no tendency for neoplastic changes. Moreover, a series of experiments showed that hTERT does not cooperate with known oncoproteins in tumorigenesis either in adrenocortical cells or in human fibroblasts. Nevertheless, hTERT was required for tumorigenesis when cells were implanted subcutaneously rather than in the subrenal capsule space. Changes in gene expression make hTERT-modified cells more robust. Understanding these changes is important so as to be able to separately control immortalization and other desirable properties of cells that could be used in cell therapy. Alternatively, desirable properties of transplants might be provided by co-transplanted mesenchymal cells: mesenchymal cell-assisted cell therapy. For both hTERT modification and mesenchymal cell-assisted cell therapy, genomics approaches will be needed to define what genetic modifications are desirable and safe in cells used in cell therapy.

Animals↗
PubMed2006

Estrogen receptor alpha gene polymorphism associated with type 2 diabetes mellitus and the serum lipid concentration in Chinese women in Guangzhou.

BACKGROUND: Estrogen might play an important role in type 2 diabetes mellitus pathogenesis. A number of polymorphisms have been reported in the estrogen receptor alpha (ERalpha) gene (also named ESR1), including the XbaI and PvuII restriction enzyme polymorphisms of ESR1, which may be involved in disease pathogenesis. The aim of this study was to determine whether ERX gene polymorphisms are associated with type 2 diabetes mellitus and serum lipid level. METHODS: Two hundred and ninety-nine patients with type 2 diabetes mellitus were compared with three hundred and forty-one health controls of Guangzhou in China, both were male and postmenopausal female residents at 51 - 70 years. ESR1 genotyping was performed using polymerase chain reaction (PCR) and PvuII and XbaI restriction fragment length polymorphism (PCR-RFLP) analysis. RESULTS: ESR1 allelic frequencies of P, p and X, x alleles were 0.408, 0.592; 0.360, 0.640 in the type 2 diabetes mellitus group and 0.318, 0.682; 0.328, 0.672 in the control group, respectively. In case-control study, there was significant difference in PvuII, but not XbaI, allele frequency between the type 2 diabetes mellitus and control groups (P = 0.001 and P = 0.122). When the group was separated into men and women, the difference was significant in women (P < 0.001) but not in men (P = 0.854) with the PvuII genotype, and the effect of PvuII variant on the development of type 2 diabetes mellitus was improved with aging. In addition, PvuII genotype was associated with blood glucose [fasting blood glucose (FBG), postprandial blood glucose (PBG)] and serum lipid [total cholesterol (TC) and low density lipoprotein (LDL)-c] concentration in healthy women. CONCLUSIONS: PvuII polymorphism of ESR1 increases susceptibility to type 2 diabetes mellitus in Chinese Guangzhou women. ESR1 variants may also impact serum lipid metabolism, which might provide a mechanism connecting ESR1 to type 2 diabetes.

Aged↗
PubMed2006

Diazoxide prevents diabetes through inhibiting pancreatic beta-cells from apoptosis via Bcl-2/Bax rate and p38-beta mitogen-activated protein kinase.

Increased apoptosis of pancreatic beta-cells plays an important role in the occurrence and development of type 2 diabetes. We examined the effect of diazoxide on pancreatic beta-cell apoptosis and its potential mechanism in Otsuka Long Evans Tokushima Fatty (OLETF) rats, an established animal model of human type 2 diabetes, at the prediabetic and diabetic stages. We found a significant increase with age in the frequency of apoptosis, the sequential enlargement of islets, and the proliferation of the connective tissue surrounding islets, accompanied with defective insulin secretory capacity and increased blood glucose in untreated OLETF rats. In contrast, diazoxide treatment (25 mg.kg(-1).d(-1), administered ip) inhibited beta-cell apoptosis, ameliorated changes of islet morphology and insulin secretory function, and increased insulin stores significantly in islet beta-cells whether diazoxide was used at the prediabetic or diabetic stage. Linear regression showed the close correlation between the frequency of apoptosis and hyperglycemia (r = 0.913; P < 0.0001). Further study demonstrated that diazoxide up-regulated Bcl-2 expression and p38beta MAPK, which expressed at very low levels due to the high glucose, but not c-jun N-terminal kinase and ERK. Hence, diazoxide may play a critical role in protection from apoptosis. In this study, we demonstrate that diazoxide prevents the onset and development of diabetes in OLETF rats by inhibiting beta-cell apoptosis via increasing p38beta MAPK, elevating Bcl-2/Bax ratio, and ameliorating insulin secretory capacity and action.

Animals↗
PubMed2006

Successful implantation of intravenously administered stem cells correlates with severity of inflammation in murine myocarditis.

The present study was designed to determine whether cardiac inflammation is important for the successful homing of stem cells to the heart after intravenous injection in a murine myocarditis model. Male Bagg albino/c mice were infected with encephalomyocarditis virus (EMCV) to produce myocarditis. Subgroups of mice received single injections by tail vein of embryonic stem cells (ESCs) transfected with green fluorescent protein (GFP) as a marker at days 3, 14, or 60 after infection; other subgroups without stem cell injections were killed at each of these time points to assess the degree of inflammation present. The surviving mice were killed at day 90 after virus infection and hemodynamics, gross pathology, histology, and inflammatory cytokine production in the hearts were measured. Our results indicate that myocardial inflammation was most severe and cytokine production highest at day 14 after EMCV inoculation, and in particular, was strongly positive for interleukin 6. Mice receiving intravenous ESC injections on day 14 after EMCV inoculation showed the largest number of GFP-positive cells at the time of death and the greatest functional improvement compared to uninfected controls without inflammation. We conclude that factors released from myocardium during inflammation are important for enhancing the homing, migration, and implantation of systemically infused stem cells.

Animals↗
PubMed2006

Prolymphocytoid transformation of follicular lymphoma with coexpression of CD5 and CD10.

Histologic transformation of follicular lymphoma is usually to a diffuse large B-cell lymphoma. We present a rare example of a histologic transformation of follicular lymphoma manifested by prolymphocytoid morphology and an unusual immunophenotype characterized by coexpression of CD5 and CD10. The transformed prolymphocytoid lymphoma was positive for CD5 and CD10 antigens by both flow cytometry and immunohistochemistry. The case also expressed bcl-2 and bcl-6 proteins, and exhibited t(14;18), consistent with derivation from a pre-existing follicular lymphoma. Polymerase chain reaction analysis of the immunoglobulin kappa light chain genes derived from the follicular lymphoma and prolymphocytoid lymphoma showed identical rearranged bands, suggesting clonal identity of the two neoplasms. The basis for coexpression of CD5 and CD10 remains unclear. Because the preceding low-grade follicular lymphoma was positive only for CD10 and did not express CD5, CD5 expression appears to be an acquired phenomenon accompanying the process of histologic transformation in this particular case. Prolymphocytoid transformation, similar to other histologic forms of transformation of follicular lymphoma, appears to accompany clinical progression of disease.

Adult↗
PubMed2006

Hodgkin lymphoma-like posttransplant lymphoproliferative disorder (HL-like PTLD) simulates monomorphic B-cell PTLD both clinically and pathologically.

Although Hodgkin lymphoma-like posttransplantation lymphoproliferative disorder (HL-like PTLD) has been grouped with classic Hodgkin lymphoma type PTLD (HL-PTLD), controversy remains as to whether it is truly a form of HL or whether it should be more appropriately classified as a form of B-cell PTLD. Because only few cases of HL-like PTLD have been reported, their pathologic nature and clinical behavior have not been well defined. This report characterized 5 cases of HL-like PTLD with respect to their immunophenotype, EBV status, clonality, and clinical outcome. All of the patients were male, with ages ranging from 1.5 to 55 years at diagnosis. PTLD developed from 4 months to 6 years following solid organ transplantation (3 hearts, 1 kidney, 1 liver), and involved both nodal and extranodal sites. All were EBV-related (EBER+) with the large neoplastic cells CD20/CD79a positive but CD15 negative. Immunoglobulin gene rearrangements were detected in 3 of 5 tested. All patients were managed by initial reduction/withdrawal of immunosuppression, with 2 also receiving chemotherapy for non-HL. Three patients died of progressive disease within 2 to 3 months after diagnosis, 1 is alive and well 2 years later, and the fifth was disease free but died of unrelated causes (graft coronary disease) 2 years later. We conclude that, although HL-like PTLD morphologically simulates classic HL PTLD, there are important immunophenotypic, molecular genetic, and clinical differences, suggesting it is in fact most often a B-cell PTLD. Distinction between HL and HL-like PTLD may be important for clinical management and prognosis.

Adolescent↗
PubMed2006

Gene transfer to the gastrointestinal tract after peroral administration of recombinant adeno-associated virus type 2 vectors.

OBJECTIVES: The transfer of exogenous genetic material to cells within the gastrointestinal (GI) tract has many potential therapeutic applications. An attractive feature of the GI tract for gene transfer is its accessibility through the orogastric route. In this study, we evaluated the stability of recombinant adeno-associated virus type 2 (rAAV2) vectors within the GI tract and whether rAAV2-mediated gene transfer could be increased through manipulation of the intraluminal environment. METHODS: The stability of rAAV2 vectors carrying beta-galactosidase and enhanced green fluorescence protein transgenes was determined in the presence of hydrochloric acid, pepsin, trypsin, chymotrypsin gastric fluid and intestinal fluid and after in vivo administration. For in vivo experiments, the rAAV2 vector carrying the beta-galactosidase transgene was administered perorally to FVB/NJ mice. Groups of mice received the vector alone or in combination with sodium bicarbonate and aprotinin. Gene transfer to the stomach and small intestine was evaluated by polymerase chain reaction and histochemical assays. RESULTS: The stability of rAAV2 was reduced by hydrochloric acid, trypsin, chymotrypsin, gastric fluid and intestinal fluid. The vector was not stable within the lumen of the GI tract. Gastric acid neutralization with sodium bicarbonate and protease inhibition with aprotinin increased the in vivo stability of the vector and the level of gene transfer to the stomach and all regions of the small bowel. In both groups of mice (vector alone and vector plus sodium bicarbonate and aprotinin), transgene-derived protein expression (beta-galactosidase) was below the level of detection of the histochemical assay. CONCLUSIONS: Recombinant AAV2 are adversely affected by physiological conditions within the proximal GI tract. Gastric acid neutralization and inhibition of intestinal protease activity improved rAAV2 stability and increased the level of gene transfer within the GI tract. Despite these changes, transduction of the GI tract after peroral rAAV2 administration remained low.

Animals↗
PubMed2006

Extranodal Rosai-Dorfman disease involving the bone marrow: a case report.

Sinus histiocytosis with massive lymphadenopathy (SHML), also known as Rosai-Dorfman disease, is a very rare disorder of unknown etiology. Although classical SHML usually presents as massive, painless, bilateral neck lymph node enlargement, approximately 25% to 40% of SHML cases described to date present in extranodal organs or tissues, such as skin, upper respiratory tract, and bone etc. However, bone marrow as a site of initial presentation by SHML has not been described since the disease was initially recognized in 1969. Here, we report the first case of bone marrow involvement by extranodal SHML, which occured in a 73 year-old man with a history of refractory idiopathic thrombocytopenia purpura. The bone marrow biopsy demonstrates the distinctive and characteristic morphologic and immunophenotypic features of extranodal SHML.

Aged↗
PubMed2006

Lineage determination of CD20- B-Cell neoplasms: an immunohistochemical study.

We studied 61 CD20- B-cell lymphomas, including 29 cases of precursor B-cell lymphoblastic leukemia/lymphoblastic lymphoma (B-ALL/B-LBL), 25 cases of CD20- recurrent mature B-cell lymphoma after rituximab therapy, and 7 cases of CD20- diffuse large B cell lymphoma (DLBCL). We used markers specific for B lineage: CD79a, Pax-5, OCT.2, and BOB.1. All B-ALL/B-LBLs expressed Pax-5 (29/29 [100%]), 25 (93%) of 27 expressed BOB.1, 23 (79%) of 29 expressed CD79a, and 6 (22%) of 27 expressed OCT.2. The percentages of cases expressing Pax-5, CD79a, OCT.2, and BOB.1 in CD20- recurrent mature B-cell lymphomas after rituximab treatment were 88% (21/24), 84% (21/25), 81% (17/21), and 73% (16/22), respectively. CD20- DLBCLs rarely express routine B-lineage markers, such as and CD79a and Pax-5, but they expressed OCT.2 or BOB.1. Pax-5, BOB.1, and CD79a antigens are the most reliable B-lineage markers for paraffin immunophenotyping B-ALL/B-LBL. CD79a and Pax-5 should be used as the first-line B lineage-specific markers for rituximab-treated CD20- mature B-cell lymphomas. If negative, OCT.2 or BOB.1 may be useful. The newly identified B-lineage markers, OCT.2 and BOB.1, may be the most useful for the B-lineage determination of CD20- plasmablastic or primary effusion subtypes of DLBCL.

Antibodies, Monoclonal↗
PubMed2006

Comparison of ancillary studies in the detection of residual disease in plasma cell myeloma in bone marrow.

Morphologic determination of residual plasma cell myeloma is often difficult. This study was conducted to evaluate the diagnostic value of several ancillary methods. A total of 121 bone marrow specimens from patients with myeloma after bone marrow transplantation or chemotherapy were studied. Of those, 49 cases were studied by conventional cytogenetics (CC), 86 by flow cytometry (FC), 50 by immunohistochemical analysis, 72 by molecular studies (MS) for immunoglobulin gene rearrangements, and 18 by standard fluorescence in situ hybridization (FISH) study. Of the patients, 70 were found to have residual myeloma. Residual disease was detected in 58 of 70 patients by morphologic examination (detection rate, 83%), 25 of 26 by immunohistochemical analysis (96%), 39 of 54 by FC (72%), 6 of 40 by CC (15%), 6 of 12 by FISH (50%), and 24 of 40 by MS (60%). Among the ancillary studies, immunohistochemical analysis and FC were the most helpful ancillary studies for detection of residual disease in myeloma, with immunohistochemical analysis the most effective single method.

Adult↗
PubMed2006

Composite recurrent hodgkin lymphoma and diffuse large B-cell lymphoma: one clone, two faces.

We describe a composite lymphoma with recurrent Hodgkin lymphoma and diffuse large B-cell lymphoma components manifesting as a single, perforated small intestinal tumor in a 56-year-old man with a history of classical Hodgkin lymphoma and recent relapse in the bone marrow. The resected mass had 2 morphologically and immunophenotypically distinct components; 1 showed a pleomorphic cellular infiltrate with fibrosis and contained numerous, large Hodgkin/Reed-Sternberg-like cells and variants. The tumor cells were CD30+ and focally positive for CD15 but CD20-, CD79a-, and PAX-5-. In situ hybridization for Epstein-Barr virus (EBV) was strongly positive in the large pleomorphic tumor cells. The adjacent component displayed sheets of relatively uniform, large lymphoid cells with typical morphologic features of diffuse large cell lymphoma. The tumor cells showed uniform expression of tested B-cell antigens, absence of CD30 or CD15, and complete absence of EBV-encoded RNA. Separate molecular studies with immunoglobulin heavy and k light chain gene rearrangements clearly demonstrated an identical rearrangement pattern, indicating derivation from the same clone, which was confirmed by direct DNA sequencing analysis. Such distinctly different morphology, immunophenotype, and EBV status in different components within a clonally related single tumor mass is striking.

Antigens, CD↗
PubMed2005

DNA index determination with Automated Cellular Imaging System (ACIS) in Barrett's esophagus: comparison with CAS 200.

BACKGROUND: For solid tumors, image cytometry has been shown to be more sensitive for diagnosing DNA content abnormalities (aneuploidy) than flow cytometry. Image cytometry has often been performed using the semi-automated CAS 200 system. Recently, an Automated Cellular Imaging System (ACIS) was introduced to determine DNA content (DNA index), but it has not been validated. METHODS: Using the CAS 200 system and ACIS, we compared the DNA index (DI) obtained from the same archived formalin-fixed and paraffin embedded tissue samples from Barrett's esophagus related lesions, including samples with specialized intestinal metaplasia without dysplasia, low-grade dysplasia, high-grade dysplasia and adenocarcinoma. RESULTS: Although there was a very good correlation between the DI values determined by ACIS and CAS 200, the former was 25% more sensitive in detecting aneuploidy. ACIS yielded a mean DI value 18% higher than that obtained by CAS 200 (p < 0.001; paired t test). In addition, the average time required to perform a DNA ploidy analysis was shorter with the ACIS (30-40 min) than with the CAS 200 (40-70 min). Results obtained by ACIS gave excellent inter-and intra-observer variability (coefficient of correlation > 0.9 for both, p < 0.0001). CONCLUSION: Compared with the CAS 200, the ACIS is a more sensitive and less time consuming technique for determining DNA ploidy. Results obtained by ACIS are also highly reproducible.

Journal Article↗
PubMed2005

Survival role of protein kinase C (PKC) in chronic lymphocytic leukemia and determination of isoform expression pattern and genes altered by PKC inhibition.

Recent studies have suggested that protein kinase C (PKC) activation plays an important role in survival of chronic lymphocytic leukemia (CLL). In order to characterize the role of PKC in CLL, we investigated the expression pattern of PKC isoforms in CLL cells (7 cases) and evaluated the effect of PKC inhibition on the survival of CLL cells (20 cases). Expression of the classical PKC isoforms beta and gamma, the novel isoform delta and the atypical isoform zeta was seen in all analyzed patient samples by Western blot analysis. Expression of the PKC isoforms alpha, epsilon, and iota was variable. Following incubation with the PKC inhibitor, safingol, CLL cells underwent marked apoptosis in all cases. In order to characterize the molecular events associated with the apoptotic effect of PKC inhibition, gene expression patterns in CLL cells were evaluated by cDNA-microarray analysis. Following safingol treatment, several genes showed marked downregulation and PKC-related proteins demonstrated decreased hybridization signals. Among these proteins, CREB and Daxx were further studied by using Western blotting, nuclear binding assay and confocal immunofluorescent microscopy. These studies showed significant inhibition of these proteins, consistent with the results of microarray gene analysis. Overall, these findings suggest that PKC activation is important for CLL cell survival and that inhibitors of PKC may have a role in the treatment of patients with CLL.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Incidental and concurrent malignant lymphomas discovered at the time of prostatectomy and prostate biopsy: a study of 29 cases.

The incidence and histologic features of malignant lymphomas discovered at the time of prostate biopsy, transurethral resection, and prostatectomy are not well documented. We searched our surgical pathology files for malignant lymphomas identified from prostate surgical specimens from 1989 to 2004. Of 4,831 cases of prostate specimens (3,405 biopsies, 266 transurethral resections, 1,160 prostatectomies) examined at the City of Hope during this period, 29 cases of malignant lymphomas involving the prostate and pelvic lymph nodes were identified (0.6%). These malignant lymphomas can be divided into two groups: 1) 18 incidental cases (0.37%) without prior history of malignant lymphoma; and 2) 11 cases (0.23%) with concurrent known malignant lymphoma. For the first group, the patients with pelvic node involvement ranged in age from 59 to 78 years (mean, 69.2 years; median, 70 years), and the patients with prostate involvement ranged in age from 45 to 78 years (mean, 64.6 years; median, 67.5 years). For the second group, the patients ranged in age from 53 to 80 years (mean, 66.8 years; median, 69 years). Diagnoses of all cases were confirmed by immunohistochemistry or molecular analysis. Ten of 18 cases in the first group involved pelvic nodes only, and the other 8 cases were primary prostatic lymphoma. Of 18 cases in the first group, 13 were small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL), 3 were marginal zone B-cell lymphoma, and 1 was mantle cell lymphoma. These lymphomas were not readily apparent in most cases by histologic examination, and may be confused with chronic prostatitis when the prostate was involved or with reactive lymphoid hyperplasia when pelvic nodes were involved. Immunohistochemistry and molecular studies may be necessary to confirm the diagnosis. For the second group, prostate and pelvic lymph nodes were involved as part of systemic dissemination of concurrent malignant lymphoma. The diagnosis was usually easily established in these cases. Of 11 cases, 4 were SLL/CLL, 4 were follicular lymphoma, 2 were mantle cell lymphoma, and 1 was diffuse large B-cell lymphoma.

Aged↗
PubMed2005

An aggressive extranodal NK-cell lymphoma arising from indolent NK-cell lymphoproliferative disorder.

Indolent NK-cell lymphoproliferative disorder, also known as chronic natural killer (NK) cell large granular lymphocytosis (leukemia), is a very rare entity in the World Health Organization (WHO) Classification of Tumors of Hematopoietic & Lymphoid Tissues. Unlike aggressive NK-cell leukemia, which is malignant, the WHO does not specify whether indolent NK-cell lymphoproliferative disorder is reactive or neoplastic. Patients with indolent NK-cell lymphoproliferative disorder are usually asymptomatic older adults who have a nonprogressive, very stable clinical course. We report an unusual case of an aggressive extranodal NK-cell lymphoma, non-nasal type, which presented as a subcutaneous tissue mass, which apparently transformed from a preexisting, untreated indolent NK-cell lymphoproliferative disorder in an 65-year-old otherwise healthy white man. The extranodal NK-cell lymphoma and the NK-cell lymphoproliferative disorder in the blood and bone marrow share a distinctive and identical NK-cell immunophenotype and genotype: CD56/CD8/TIA-1-positive and surface CD3-negative, negative for Epstein-Barr virus infection, and no evidence of T-cell and B-cell receptor gene rearrangements. To the best of our knowledge, such aggressive lymphomatous transformation in an indolent NK-cell lymphoproliferative disorder has not been previously reported.

Aged↗
PubMed2004

An extended aqueous solvation model based on atom-weighted solvent accessible surface areas: SAWSA v2.0 model.

A new method is proposed for calculating aqueous solvation free energy based on atom-weighted solvent accessible surface areas. The method, SAWSA v2.0, gives the aqueous solvation free energy by summing the contributions of component atoms and a correction factor. We applied two different sets of atom typing rules and fitting processes for small organic molecules and proteins, respectively. For small organic molecules, the model classified the atoms in organic molecules into 65 basic types and additionally. For small organic molecules we proposed a correction factor of "hydrophobic carbon" to account for the aggregation of hydrocarbons and compounds with long hydrophobic aliphatic chains. The contributions for each atom type and correction factor were derived by multivariate regression analysis of 379 neutral molecules and 39 ions with known experimental aqueous solvation free energies. Based on the new atom typing rules, the correlation coefficient (r) for fitting the whole neutral organic molecules is 0.984, and the absolute mean error is 0.40 kcal mol(-1), which is much better than those of the model proposed by Wang et al. and the SAWSA model previously proposed by us. Furthermore, the SAWSA v2.0 model was compared with the simple atom-additive model based on the number of atom types (NA). The calculated results show that for small organic molecules, the predictions from the SAWSA v2.0 model are slightly better than those from the atom-additive model based on NA. However, for macromolecules such as proteins, due to the connection between their molecular conformation and their molecular surface area, the atom-additive model based on the number of atom types has little predictive power. In order to investigate the predictive power of our model, a systematic comparison was performed on seven solvation models including SAWSA v2.0, GB/SA_1, GB/SA_2, PB/SA_1, PB/SA_2, AM1/SM5.2R and SM5.0R. The results showed that for organic molecules the SAWSA v2.0 model is better than the other six solvation models. For proteins, the model classified the atoms into 20 basic types and the predicted aqueous free energies of solvation by PB/SA were used for fitting. The solvation model based on the new parameters was employed to predict the solvation free energies of 38 proteins. The predicted values from our model were in good agreement with those from the PB/SA model and were much better than those given by the other four models developed for proteins.

Chemistry, Organic↗